It is likely that some service or program is trying to load at startup, and it is hanging your computer.
To fix this, go into Safe Mode, and run MSCONFIG. Click on the Services tab. At the bottom, check the box which says "Hide all Microsoft services".
Now go through the list of services, and uncheck everything except what you KNOW is needed. If you aren't sure, then uncheck it.
Now click APPLY and then restart the computer in Normal Mode.
You should be able to work normally now. But the problem is, there may be some needed service that is not running, because you disabled it in MSCONFIG. For example, you might have disabled Adobe Updater, and so now that functionality won't be available in Windows. (You may not want Adobe Updater running; but if you do, you'll need to re-enable it.) Therefore, run MSCONFIG, go to the Services tab, and enable the services that you think are needed. Click APPLY, and reboot the computer.
If the computer is still working well, then you could go into MSCONFIG and enable a few more services, APPLY, and reboot, to see if everything is still ok.
At some point in this process, the computer will hang when you reboot it; at that point, you will know what was causing the problem -- it was one of the services you just enabled.
Of course, you don't have to re-enable anything. You may prefer to leave all of the non-Microsoft services disabled. But if you do that, some things aren't going to work.
If the above procedure doesn't fix the hanging problem, then there is some other issue involved. But the fact that you can work without a problem in Safe Mode tells me that the above is exactly what is causing the problem.
Good luck!
